On-chip measurement of the Brownian relaxation frequency of magnetic beads using magnetic tunneling junctions

M. Donolato, E. Sogne, Bjarke Thomas Dalslet, M. Cantoni, D. Petti, J. Cao, F. Cardoso, S. Cardoso, P. P. Freitas, Mikkel Fougt Hansen, R. Bertacco

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    Abstract

    We demonstrate the detection of the Brownian relaxation frequency of 250 nm diameter magnetic beads using a lab-on-chip platform based on current lines for exciting the beads with alternating magnetic fields and highly sensitive magnetic tunnel junction (MTJ) sensors with a superparamagnetic free layer. The first harmonic out-of-phase component of the MTJ response gives the imaginary part of the magnetic bead susceptibility, which peaks at the Brownian relaxation frequency. This work paves the way to on-chip implementation of Brownian magnetorelaxometry in innovative "lab-on-a-bead" assays for biomolecular recognition. (C) 2011 American Institute of Physics. [doi:10.1063/1.3554374]
    Original languageEnglish
    JournalApplied Physics Letters
    Volume98
    Issue number7
    Pages (from-to)073702
    ISSN0003-6951
    DOIs
    Publication statusPublished - 2011

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